Miniature very high frequency transducers are needed for imaging and measuring blood flow in the heart of a mouse embryo for a better understanding of the development of congenital heart diseases in the fetus in utero. The current trend is towards earlier in utero diagnosis and management of congenital heart diseases in the fetus. This has been made possible by the improvement in image quality of ultrasonic scanners in past few years. VHF transducers have to be used here because of the small size of the mouse heart. Focused PVDF transducers at 40 MHz have been used in an Ultrasonic Backscatter Microscopy (UBM) to obtain B-mode images of mouse embryos. The current goal is to increase the frequency to beyond 50 MHz and to increase the frame rate of the UBM to the extent that it allows for the imaging of the beating embryonic heart. The UBM system will be augmented with 50 MHz Doppler probes that can be used to measure blood flow characteristics and heart functions in the early embryonic heart. Transducers using a modified lead titanate (PT) which has a lower dielectric constant (220) than PZT at 50 MHz with a 3.5 f number, 65 MHz with a 2.4 f number, and 95 MHz with a 2.4 f number have been built and tested at NYU. Linear and annular arrays with tighter focusing and higher frame rate being developed at the Resource are better suited for this application. A 50 MHz annular array is being designed and developed and will be evaluated at NYU once it is completed. [unreadable]